it would be great to be able to zoom in more then simple Alt+1 full-screen (preferably with a keystroke that would go to a predetermined customizable zoom of up to 100%) to check sharpness without having to change to darkroom mode.

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this would be specially useful when culling - before starting to develop, and particularly convenient when culling JPGs (I understand that RAWs could perhaps still need the full overhead of darkroom mode)